Originally Posted by M3DCTBT
I hold one of the higher whp charts at 407.7whp along with jonmartin at 407whp and we used modified stock x pipes. My car even hadPeople can preach all they want about x designs and pipe diameter but ive yet to see it translate on the dyno sheet.
Ive since put on a full gintani true dual x pipe but that is for the great exotic sound more then the performance.
My car puts down 398 RWHP with just our exhaust system and tune. No other mods on 91 pump.
This dyno was done at DynoExtreme here in Stanton California and they did not even use a fan in front of the car. The dyno operator along with another M3 driver there was blown away.
There is a substantial difference between the factory mid-section and a true x-design mid-section that has been systematically tuned and setup to perform all across the power band.
I personally gained roughly 13 rwhp from a cat-less stock mid-section and our actual X-pipe system.